Gaslighting, an elaborate and insidious technique of deception and psychological manipulation, usually practiced by a single deceiver, or “gaslighter,” on a single victim over an extended period. Its effect is to gradually undermine the victim’s confidence in his own ability to distinguish truth from falsehood, right from wrong, or reality from appearance, thereby rendering him pathologically dependent on the gaslighter in his thinking or feelings.

As part of the process, the victim’s self-esteem is severely damaged, and he becomes additionally dependent on the gaslighter for emotional support and validation. In some cases the intended (and achieved) result is to rob the victim of his sanity. The phenomenon is attested in the clinical literature as a form of narcissistic abuse whereby the extreme narcissist attempts to satisfy his pathological need for constant affirmation and esteem (for “narcissistic supply”) by converting vulnerable people into intellectual and emotional slaves whom he paradoxically despises for their victimhood. Because the gaslighter is himself typically psychologically disordered, he is often not fully aware of what he is doing or why he is doing it.

The term is derived from the title of a 1938 British stage play, Gas Light, which was subsequently produced as a film, Gaslight, in the United Kingdom (1940) and the United States (1944). Those dramas vividly, if somewhat simplistically, depicted some of the basic elements of the technique. These may include: attempting to convince the victim of the truth of something intuitively bizarre or outrageous by forcefully insisting on it or by marshaling superficial evidence; flatly denying that one has said or done something that one has obviously said or done; dismissing the victim’s contrary perceptions or feelings as invalid or pathological; questioning the knowledge and impugning the motives of persons who contradict the viewpoint of the gaslighter; gradually isolating the victim from independent sources of information and validation, including other people; and manipulating the physical environment to encourage the victim to doubt the veracity of his memories or perception. In the play and films, for example, a deceitful husband drives his wife to near insanity by convincing her that she is a kleptomaniac and that she has only imagined the sounds in the attic and the dimming of the gaslights in their house, which were actually the result of his searching for her aunt’s missing jewels.